The invention relates to a method for the production of a transverse fibre web with substantially parallel fibres in a fibre layer, the direction of the fibres in the fibre layer forming an angle of greater than 0xc2x0 with the longitudinal direction of the transverse fibre web.
WO-95/00318 has disclosed a method for the production of a transverse fibre web of this kind. Firstly, a longitudinal fibre web is produced, by placing yarns which are impregnated with a matrix material on a separating layer. The separating layer consists of a material which adheres to the fibre layer just sufficiently to ensure a fixed position of the yarns with respect to one another and the separating layer. Then, web parts are cut from the longitudinal fibre web. These web parts are placed next to one another, in such a manner that the fibres of the various web parts run parallel to one another and form an angle of between 0xc2x0 and 90xc2x0 with the longitudinal direction of the transverse fibre web formed in this way. Then, the separating layers of adjacent web parts are connected to one another by means, for example, of single-sided or double-sided adhesive tape which extends in the direction of the join between the adjacent web parts. The result is a separating layer which is composed of parts and has sufficient strength to be able to take up tensile forces in the longitudinal direction of the transverse fibre web formed without the fibre layer tearing.
Then, a third layer, which is fixedly connected to the fibre layer and can adopt the stabilizing function of the separating layer, is applied to the fibre layer. After this, the separating layer is removed from the transverse fibre web, an operation which is possible without the fibre layer tearing, because the separating layer is not firmly connected to the fibre layer. A transverse fibre web of this kind is used for the production of laminates comprising fibre layers lying on top of one another, with the fibres in one fibre layer running parallel to one another, but the fibres in successive fibre layers forming an angle with one another.
The drawback of the known method is that the use of a separating layer which has to be removed entails considerable costs, for example with regard to processing of waste. Particularly when processing the most common fibres used, the use of a separating layer has an adverse effect on the production costs. The relationship between the costs of waste processing and the costs of the end product is too high when fibres of this kind are used.
The object of the present invention is to provide a method for the production of a transverse fibre web in which it is not necessary to use a separating layer, so that the quantity of waste is considerably reduced.
This object is achieved by means of a method for the production of a transverse fire web according to claim 1.
With the method according to the invention, the base stabilizing layer does not have to be replace, so that there is no waste, a fact which reduces the production costs.
GB-A-2.009.270 discloses a method for providing a rubber sheet with reinforcing fibres, where the fibres are made of metal or some other material which has a strength comparable to that of metal. Characteristic values for the diameter of the fibres used in this method lie between 0.1 mm and 1.0 mm. The metal elements are formed into a helix, and are formed into a longitudinal fibre web by coating the fibres metal elements with rubber. The resulting fibre web has sufficient thickness and strength for handling the sheet without the necessity of applying a separate carrier layer or stabilizing layer. For forming a transverse fibre web, web parts are cut off of the longitudinal fibre web and attached to one another in a transverse direction.
This publication does not disclose a cross-ply, i.e. a textile product having two or more fibre layers, wherein the fibre directions in successive fibre layers form an angle with respect to one another. The rubber sheet with transverse metal reinforcing elements formed by the method as disclosed in the publication is used as reinforcement in tires, for instance for vehicles. The thickness of the transverse fibre web of this publication is larger than the diameter of the fibres employed.
The diameter of the fibres employed in the method according to the invention is less than 50 xcexcm, with the possibility, for example, of using fibres which have a diameter of 10 xcexcm or even less. The thickness of the base stabilizing layer and the eventual second stabilizing layer employed is of the same order of magnitude. Moreover, the fibres in the fibre layer bear against one another, so that the ratio of the weight of fibres to the total weight of the base stabilizing layer and the eventual second stabilizing layer is as high as possible.
FR-A-1.595.577 relates to a method for the production of a cross-ply, wherein a transverse fibre web is produced as an intermediate product. Fibres are arranged in the longitudinal direction on a thermoplastic stabilizing layer with a thickness of between 0.5 and 1 mm.
Web parts are cut off the longitudinal fibre web produced in this way, which comprises one base stabilizing layer and one fibre layer, which web parts are then attached to one another in such a manner that the transverse fibre web is formed. A second layer of fibres is then arranged on that side of the thermoplastic stabilizing layer which is situated opposite the fibres, in the longitudinal direction of the transverse fibre web. The result is a cross ply which comprises a thermoplastic stabilizing layer with fibres on both sides, which fibres form an angle with one another. The web parts are attached to one another by placing an edge section of one web part over an edge section of another web part, and by thermally welding the overlapping edge section to each other. The method disclosed in this publication also does not allow the production of a transverse fibre web having a thickness of less than 50 xcexcm.
A further advantage or the method according to the invention can be achieved if the material used for the base stabilizing layer has properties which are suitable for the end product which is produced from the transverse fibre web. It is particularly advantageous to use a film, a fibre fabric or a thermosetting material for the base stabilizing layer.
Further advantage is obtained if an identical material is used far the base stabilizing layer, the fibre layer and the second stabilizing layer. End products which are produced from the transverse fibre web according to the invention cam be recycled in a simple manner at the end of a service life cycle.
Preferably, the longitudinal sides of the longitudinal fibre web are formed in such a manner that they are complementary to one another, with the result that a strong join can be formed between the web parts.
Further advantage results if a transverse fibre web is used for the base stabilizing layer, so that a cross ply is formed. The cross ply is immediately ready for further processing.
The invention also relates to a transverse fibre web which is produced using the method according to the invention.
The invention furthermore relates to a device for the production of a cross ply, which uses a transverse fibre web which is produced using the method according to the invention.